BMW, VW investigating how thermoelectrics may juice up future automobiles
by Jeremy Korzeniewski on Feb 10th 2009 at 8:34AM 
Volkswagen has supposedly created a device that generates electricity from the wasted heat created by an internal combustion engine. The device, known as a thermoelectric generator (TEG), relies on the reaction of two different metals as heat passes through, thereby generating electricity. According to VeeDub, its TEG can generate an impressive 600 Watts, which is about 30% of the electrical needs of a Golf Plus and enough to reduce fuel consumption by over 5%. Last year, BMW won awards with a similar system that was able to generate about 200 Watts of power.
When gasoline is burned in an automobile, only about a quarter of the potential energy is turned into forward motion. The rest is wasted as heat. Automakers are keen to capture back a portion of these losses, but there's still a long way to go before a TEG like this is practical. Regardless, it's a technology that has plenty of promise if it's adopted on a large scale.
[Source: Gizmag]
Reader Comments (Page 1 of 1)
jlee 9:09AM (2/10/2009)
I do research on TEG's at MSU!!!!
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scappy 9:26AM (2/10/2009)
I have a great use for all of this ethanol the corn lobby wants us to use. Instead of adding it to our fuel, how about we use it in a closed loop heat exchanger to generate power off of the exhaust. Liquid ethanol, to a vapor, drives a turbine, through another radiator and back.
I thought BMW was working on something like this too.
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matt 9:27AM (2/10/2009)
I did an experiment for my physical chemistry class and everyone in my class got 5-15% efficiency for gasoline engines in cars, not 25%...
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gslippy 10:20AM (2/10/2009)
Thermoelectrics are fabulously expensive, so they are definitely a long way off.
Moreover, 600 Watts is equal to only 0.80 Horsepower, so any hope of using this energy for motive power is not practical. But it would save on the energy scavenged by the electrical system, as the article describes. 200 Watts might be enough to operate the lighting system, for instance.
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robotrock 10:30AM (2/10/2009)
I admit I'm kind of an idiot when it comes to anything science related, but I have wondered why a small steam engine couldn't be run off the hot exhaust gases?
Hot goes out, generates steam in a closed loop system that creates electricity.
Might not be enough to run a car but maybe enough to run the radio or keep the batteries charged.
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Russ Owens 10:47AM (2/10/2009)
Actually companies are looking into this.
BMW developed their Steamer concept system (http://www.greencarcongress.com/2005/12/bmw_developing_/comments/page/2/).
Honda has a Rankine cycle based system (http://www.greencarcongress.com/2008/02/honda-researchi.html)
why not the LS2LS7? 11:46AM (2/10/2009)
It's more efficient to use the hot exhaust gases to run a turbocharger instead.
Russ Owens 10:45AM (2/10/2009)
Thermoelectrics (TE) are not intended to provide motive power, but to reduce the parasitic losses from the alternator generating electric power. The 600W rating was likely a peak rating, not an average power. Like another person mentioned they are currently very expensive (and will likely be for many years) . The output power depends on the exhaust heat/temperature, which is low for light-duty vehicles. They make more sense for large displacement diesel engines that have much higher exhaust heat. Higher efficeincy engines, engines used in hybrid systems, and engines running HCCI/PCCI will have even less heat so will make TE even more challenging to use cost-effectively. A recent presentation by an auto industry technology expert addressed TE agreed, also mentioning that Toyota and others have tried them but hvae not moved to production because of cost, perofrmance, and durability.
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BoneHeadOtto 2:17PM (2/11/2009)
I have always heard this about TEs and it makes me wonder. If eliminating electrical parisidic loss is important, then why dont we have the equivalent of a plug-in hybrid with no hybrid? Im meaning a standard gas engine with batteries supporting the non-motive electrical load. If on long trips you deplete the charge, the you simply clutch engage the alternator agian. If parisidic loss is substantial, then this cheaper simpler system would boost your city mileage.